Hitchcocks Forum

Hello, happy new year to everyone, mine isn't starting as it should , the bike anyway...
To resume things , my 350 is in trials trim (plus sidecar) and has been running perfectly for the last 4 racing seasons.It's fitted with trial exhaust and kn filter so bigger pilot and main jets and "richer" slide.
Until the 15 of december it started , run and held its idle perfectly.
Then starting became difficult so I decided it was time for a new spar plug (iridium as before), new air filter (same model but new) and a carb clean.Also fitted a new fuel fliter and cleaned the tank.
Now she'll start but will only run for a second or two and then cut , that's with the choke on , without no starting at all.
If I try to open the throttle she cuts straight away.
No "funny" noises , no kick back.
It feels like it's getting either to much petrol , could the micarb be "used" and letting to much petrol in ?
Or the opposite ?But carb has been cleaned 3 times....
Any ideas welcome,
Thanks very much in advance

Forgot to add that it's fitted with a Boyer electronic ignition , carb float level is in the middle of our host's recommendation .....just had another go , spark plug looks "wet"....

Sounds fuel starved on the pilot side,from what you say the choke/starter jet is clear.Has the pilot jet been clear/clean the 3 times you`ve done it? Have you tried without choke but covered 90% of the carb intake to act as another choke but use your pilot jet this way?

Does sound like fuel starvation/weak mixture. Is the intake manifold rubber in good condition and not perished or cracked? If you have cleaned the tank presumably the fuel was ok and not contaminated with water? Have you tried fresh fuel? If all looks good carb side turn your attention to the ignition and check for a healthy strong spark with a clean dry plug. Unlikely to be a worn carb or jet size issue if one minute it was running perfectly and the next like this.

Thanks for your ideas , I've checked for air leaks , in fact when I used the bike for the last time , mid december, I ran her on the reserve for the first time since a very long time , and when I dismanteled the carb the pilot jet was coated with a kind of white gel, the lower part of the fuel filter , in the tank , was also coated with it .So maybe , despite my efforts, there's still a blockage somewhere.

Don`t mention GELL or fuel going OFF on here!

Could the white gel be a water-fuel emulsion? That wouldn't burn too well. Might be worth draining and cleaning the tank, then draining the carb again.

Better if I use rude french words!!!???
Last trials seems to show a weak spark , but the ignition is Boyer and powerbox , so no battery, should the spark be nice and blue?
Wich could mean that carb is ok but that I inadvertently messed things up in the wiring when I cleaned the bike ...

Tank was drained , petrol tap also .....so it's either something still in the carb or something I caused when cleaning the bike , would a weak ignition allow the bikze to run for a brief time then die?.....

I think you need that carb off again and really get into the corners. Do you have an airline? If not I would try to get somewhere that has to blow everthing through.